Abstract: The invention relates to an above sea-level platform, for use as, for example, an oil-rig, which is connected to a sea-bed foundation by a ball-joint arrangement. For protection, the ball joint is hollow and partially received in a recess at the lower end of a tubular extension of the platform through which an oil conduit leads from the foundation via the hollow ball joint, the two parts of which are held in sealing abutment by a draw member.